An inflatable vehicle occupant protection device, such as an air bag, is inflated upon the occurrence of a vehicle crash. The air bag is part of an apparatus which further includes a crash sensor and an inflator. The crash sensor senses vehicle conditions that indicate the occurrence of a crash. When the crash sensor senses a crash-indicating condition of at least a predetermined threshold level, the inflator is actuated and emits inflation fluid which inflates the air bag into the vehicle occupant compartment. The air bag can then engage a vehicle occupant to help restrain the occupant.
The manner in which the air bag engages the vehicle occupant can be influenced by the inflation fluid pressure in the air bag. The inflation fluid pressure, in turn, can be influenced by the ambient temperature.